Duke3D: Changing the input struct members horz and avel has no effect

As reported here: https://forums.duke4.net/topic/11419-set-input-avel-to-zero-has-no-affect-in-r9257/

Since the mouse input changes from r8551 (d8a523e5), it is no longer possible to alter the player's angular and horizontal velocity through the corresponding input struct member. In particular, it is no longer possible to lock it in place through the following code:

onevent EVENT_PROCESSINPUT
        seti .avel 0 // has no effect
        seti .horz 0 // has no effect

        seti .fvel 0 //work properly
        seti .svel 0 //work properly
endevent

Note that getting the values stored in avel and horz still works as before. If this is an intentional change, feel free to close this issue.